If compression test show 170psi it means its not too low and its not too high for detonation to be happen. Here you can read more if this isnt familiar to you Understanding compression on a pump gas street motor - Engine Masters it is written by David Vizard who also knows engines.
Dissapointing performance
- Thread starter Dusterguy
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It is blindingly clear to ME after the ink pen spring comment that all of you are getting taken for a Finnish Duster ride. LOL
Sorry I cant follow what you said. You mean Im joking here? I can show pics of that spring and dist. if you like.
Coronet 500
Well-Known Member
Yes, I think you are a joke.
Hey great article for a single cylinder test. I forgot is this a lawnmower?
Hey great article for a single cylinder test. I forgot is this a lawnmower?
You forgot to be funny.
Coronet 500
Well-Known Member
Why don't you get off the keyboard, listen to these guys and fix you friggin' car you loser.
C'mon--Take it easy in here please.....
RAMM
Well-Known Member
What cylinder did you perform compression test on? Consider this: Lets say that whatever cylinder you tested had the worn lobe--you would have much less duration/lift and therefore an artificially high reading on the gauge. Its happened to me, that's how I know. I had a cam fail on me (used a different oil than normal) but didn't know it. I pulled # 4 plug and cranked it over after dyno testing and saw 205 psi when experience tells me it should have been 170 psi. Guess what? The others tested @ 175 psi but the one I chose to start with cranked 205 psi, guess which intake lobe was worn off? J.Rob
Seriously? I thought you were a professional engine builder of sorts and you're giving this guy credence? Carry on I guess. lol
It was 2. cylinder.
I understant. I will do compression test to all cylinders later tomorrow.
RAMM
Well-Known Member
Just trying to help triple R, but am nearing the end of my rope rapidly. If everything checks out as perfect then he is missing something or has no idea of how to diagnose/troubleshoot or does not believe what only he can see. J.Rob
I think the cam is not where you think it is. how far down in the whole are those stock pistons. pick one.
at this point I believe, a spark in time is not the problem.
at this point I believe, a spark in time is not the problem.
GeorgeH
Well-Known Member
I thought my estimate was a bit light after I posted it. lolWow.. I have nothing to add other than the number of years experience in this thread is not 100 years, closer to 200+ LOL
Putting a bandaid on a cut artery, best of luck with it. Black Knight it all the way...
I have decreed it 2 times. It is right. I have kb107 pistons, not stock pistons. Pistons are 0.0157" down in hole (0.4 millimeter). Heads milled to 65cc by imms engines. Tests what I have made erlier have shown that it likes less timing at low rpm. (centrifugal timing comes too fast in)
GeorgeH
Well-Known Member
I think he might have a problem with the cam phasing. I have seen where changing the phasing from 4 adv to straight up to 4 retarded change cylinder psi. from 165 to 195 and totally change the characteristics of the engine. 4 advanced a bottom end powerhouse and 4 degrees retarded killed all the bottom end. He swears the cam is in right, but that he has a fair amount of chain slack. so....... Just one of those things where a guess just isn't good enough.
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just a guess ? after 2 times
I set it to where comp advice to set it. I can check cam card to confirm it. Sure I had cam card with me when I decreed the cam, but right now I cant remember it.
nm9stheham
Well-Known Member
For what it may be worth, I have not been able to follow all of this thread, but I recomputed the SCR and DCR with the latest data provided by the OP and come up with 9.9 SCR and 8.1 DCR. If all of the cylinders pressures are around 170 psi, then this all makes sense and indicates that the cam timing is probably pretty close to correct (106 ICL).
This ought to be a pretty torquey engine if the ignition timing is close to correct. Low RPM torque should not be badly lowered by the exhaust restrictions. But not being able to spin the tires says there may be problems with either the rear gear or the low RPM torque converter.
OP, is this TC an electric lockup type? You mention that it is a custom made TC with lockup? Can you provide more information on this TC?
And BTW, OP, with the heads shaved to 65 cc, the chambers are smaller and so typically a few degrees less ignition advance is needed.
I am a bit confused on the heads. Can you describe them in more detial? I thought these were RHS with 62 cc chambers but then you list the heads as being shaved to have 65 cc chambers.
This ought to be a pretty torquey engine if the ignition timing is close to correct. Low RPM torque should not be badly lowered by the exhaust restrictions. But not being able to spin the tires says there may be problems with either the rear gear or the low RPM torque converter.
OP, is this TC an electric lockup type? You mention that it is a custom made TC with lockup? Can you provide more information on this TC?
And BTW, OP, with the heads shaved to 65 cc, the chambers are smaller and so typically a few degrees less ignition advance is needed.
I am a bit confused on the heads. Can you describe them in more detial? I thought these were RHS with 62 cc chambers but then you list the heads as being shaved to have 65 cc chambers.
Thanks for taking time to calculate it. I have came up almost same numbers as you did. Engine feels somewhat crisp and good thorttle response even at low rpm, but when I floor it 100% then there isnt that much happening.
TC is made by local reputable builder here and has 2200 stall speed. No electric lock-up it all mechanical/oil pressure.
IMMENGINES.COM These are exactly the heads and I ordered them with 65cc and I assume they are milled to that.
nm9stheham
Well-Known Member
Ok, thanks: there are enough heads and variations out there that I have problems remembering them all. The heads should not be the problem. We have Edelbrocks with similar flows, and very close to the same SCR/DCR and with 3.55 rear gears and a 2500 stall TC, it will spin the tires pretty good. (We have actually not yet floored it from a dead stop in 1000 miles LOL, but 1/2 or 2/3 throttle with a little turn on the steering wheel and it will spin and set the car sideways immediately.)
I will tell one story that might help give some perspective. I had a 1970 Ranchero with a well built 351C, with a bit over 10:1 SCR, low 8's DCR, and a low duration, high lift cam that was a great torque engine. I always estimated it at around 350-375 ft lbs torque and around 325 or a bit more HP. It had a 3.08 rear gear and stock TC, with the stall speed probably below 2000 RPM. It would spin the tires some but was not a tire burner. It would always beat stock 440 Mopars in street drag races but in looking back after having several rally and other cars, it was not a great machine off the line. It figured that the low rear gear and stock TC loaded down the engine at a lower than optimum RPM. Once it got rolling just a bit, it took off great.
I tend to think that you have a similar situation with your 2.94 gear and 2000 RPM TC. It is just never going to take off like a rocket. Your engine is just not up on the torque curve when the TC starts to lock up. I am willing to bet that you can tune the ignition and cam timing all over the place and it won't change things much at take off. I know this has been said before, but I hope my above similar build helps with perspective. If you had a manual transmission, you could just rev the engine more and slip the clutch as you took off and it would be all better.
IMHO, the exhaust is likely just going to hurt the top end RPM range. When I went from headers to standard exhaust manifolds on the above 351C engine, the top end suffered the most. It is not great, but I think that any exhaust reversion is a minor factor and is not huge at 2000 RPM; your cam is not all that radical.
I will tell one story that might help give some perspective. I had a 1970 Ranchero with a well built 351C, with a bit over 10:1 SCR, low 8's DCR, and a low duration, high lift cam that was a great torque engine. I always estimated it at around 350-375 ft lbs torque and around 325 or a bit more HP. It had a 3.08 rear gear and stock TC, with the stall speed probably below 2000 RPM. It would spin the tires some but was not a tire burner. It would always beat stock 440 Mopars in street drag races but in looking back after having several rally and other cars, it was not a great machine off the line. It figured that the low rear gear and stock TC loaded down the engine at a lower than optimum RPM. Once it got rolling just a bit, it took off great.
I tend to think that you have a similar situation with your 2.94 gear and 2000 RPM TC. It is just never going to take off like a rocket. Your engine is just not up on the torque curve when the TC starts to lock up. I am willing to bet that you can tune the ignition and cam timing all over the place and it won't change things much at take off. I know this has been said before, but I hope my above similar build helps with perspective. If you had a manual transmission, you could just rev the engine more and slip the clutch as you took off and it would be all better.
IMHO, the exhaust is likely just going to hurt the top end RPM range. When I went from headers to standard exhaust manifolds on the above 351C engine, the top end suffered the most. It is not great, but I think that any exhaust reversion is a minor factor and is not huge at 2000 RPM; your cam is not all that radical.
Yeah other too have said taht I have wrong stall speed and gears. I agree with that and these are parts that im going to change in future. This car has been 2-3 years in garage and now when its working at some level Ill just want to drive it some time. But time will come when I need more performance and I will change these parts along with new exhaust and carb.
When asking other people opinion about my previous engine, almost all people said that your heads are not flowing enought to make real power. I saved money long time and buyed the best street heads that there is, imm rhs head. (thats at least what Ive been told) these heads support more than 500hp when looking at flow numbers. Now when I first tried this new combo I didnt see anywhere near 400hp (1/8 mile trap speed tells that clearly) so some of you may understand why I was heavily dissapointed to this head swap. But now I know what I need to do next. (change the parts you have been adviced to do)
nm9stheham
Well-Known Member
IMHO:
1. The first thing I would do is the improve the exhaust since you are going to have to do that eventually to be able to use the breathing of the new heads at higher RPM's. This will be a step that you won't go back later and change. I don't think it will have a huge effect at the low RPM's.
2. The only thing I can think of to change the engine torque significantly at the low RPM's of the TC stall speed and to match the present rear gear better is to change the cam to 10-15 degrees shorter duration and keep the lift as high as you can. But this is a change that you may need to reverse later if the best drag race ET's is your most important goal. However, if you do drive this car on the road, and gas mileage is important, then the cam change will help that. If you want to stay with a solid lifter cam, I would look at the 2 smallest Lunati Voodoo solid lifter cams. You would then have to be more careful with the ignition advance to avoid detonation as you will be pushing the DCR up into the mid 8 range, and may have to limit the advance more and have it advance more slowly. Others may have better recommendations.
3. IF changing the cam seems like a waste of money, AND IF performance is the most important thing, then I would change the rear gear first. This is because in the 1/8th mile, you are not anywhere near to the best RPM range for those heads to breath. In the 1/8 mile, you need to be in the 4:1 range to get the engine to the 5500 RPM at the end of the run, and you could go a bit higher if 1/8th mile is all that you run. (I am assuming your tires are about 22" in diameter per your tire description.)
4. The rear gear change will help off the line but will not really fix the performance off of the line. Only a TC change will help. And of course it will effect trap speed; anything that makes the engine work at a lower than best possible torque will lower the trap speed if your RPM's are not being limited by the engine at the trap. Can you verify that the engine RPM's are around 4000 at the end of 1/8th mile?
5. And this is probably not the problem but are you sure the throttle is fully opening when you push the pedal to the floor?
6. I'll be curious when you check compression on all cylinders. It would be most useful to post all 8 readings.
1. The first thing I would do is the improve the exhaust since you are going to have to do that eventually to be able to use the breathing of the new heads at higher RPM's. This will be a step that you won't go back later and change. I don't think it will have a huge effect at the low RPM's.
2. The only thing I can think of to change the engine torque significantly at the low RPM's of the TC stall speed and to match the present rear gear better is to change the cam to 10-15 degrees shorter duration and keep the lift as high as you can. But this is a change that you may need to reverse later if the best drag race ET's is your most important goal. However, if you do drive this car on the road, and gas mileage is important, then the cam change will help that. If you want to stay with a solid lifter cam, I would look at the 2 smallest Lunati Voodoo solid lifter cams. You would then have to be more careful with the ignition advance to avoid detonation as you will be pushing the DCR up into the mid 8 range, and may have to limit the advance more and have it advance more slowly. Others may have better recommendations.
3. IF changing the cam seems like a waste of money, AND IF performance is the most important thing, then I would change the rear gear first. This is because in the 1/8th mile, you are not anywhere near to the best RPM range for those heads to breath. In the 1/8 mile, you need to be in the 4:1 range to get the engine to the 5500 RPM at the end of the run, and you could go a bit higher if 1/8th mile is all that you run. (I am assuming your tires are about 22" in diameter per your tire description.)
4. The rear gear change will help off the line but will not really fix the performance off of the line. Only a TC change will help. And of course it will effect trap speed; anything that makes the engine work at a lower than best possible torque will lower the trap speed if your RPM's are not being limited by the engine at the trap. Can you verify that the engine RPM's are around 4000 at the end of 1/8th mile?
5. And this is probably not the problem but are you sure the throttle is fully opening when you push the pedal to the floor?
6. I'll be curious when you check compression on all cylinders. It would be most useful to post all 8 readings.
I will post compression results tomorrow. First thing that I looked was is the throttle opening all the way and it was. I need to email PTC and ask do they make high stall converters for lockup trans and what prize.
Fuel mileage doesnt really matter to me but often I drive long trips on higway and 3.23 gears are good for that. Now engine doest scream too bad at 60 miles per hour. I understand that if I want performance these gears need to go.
Fuel mileage doesnt really matter to me but often I drive long trips on higway and 3.23 gears are good for that. Now engine doest scream too bad at 60 miles per hour. I understand that if I want performance these gears need to go.
There is a lot of gold in that statement!
If it has headers on it, remove the exhaust at the collector and see how it responds. The exhaust is KILLING the engine and NOTHING you do with the distributor will fix that. As long as you continue on the current path, accept the rotten performance you've observed.
That engine with a good tune, decent carb and exhaust will make 420hp EASY!!!
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